Microphone arrays are widely used in electronic consumer devices or other systems having a human speech interface to achieve directionality of reception. When the microphone array comprises a multitude of individual microphone circuits that include a MEMS transducer and an audio amplifier, power dissipation becomes an issue.
Each individual microphone circuit arrangement includes a voltage regulator that supplies a constant voltage to the audio amplifier independent of the supply voltage of the system. When battery powered, the supply voltage may vary in a considerable voltage range. The voltage regulator is often a so-called low-dropout (LDO) voltage regulator of which the power dissipation dependents largely on the difference between the input and output voltages. In a microphone array with many microphone circuits the overall power dissipation may be considerable when the battery is fully charged so that a large voltage difference drops at the LDO regulators. The power dissipation in the LDO regulator is converted into heat without performing another useful operational function. Hence, there is a need to reduce the power dissipation in the power supply circuitry of a microphone array.